Multiple alloys



Patented May 2 6, 1936 MULTIPLE ALLOYS Georg Schichtel, Dobriach onMillstattersee,

Austria,

assignor to American Magnesium Metals Corporation, Pittsburgh, Pa., acorporation of Delaware No Drawing.

Serial No.- 656,765. 1932 Claims.

which is obtained by the use of magnesium in excess of 80 per cent.while such alloy will be characterized by higher resistance to corrosionand at the same time will have a higher strength than the known alloysof this kind.

The known alloys in use containing generally more than 85% magnesium andas principal additional ingredient aluminum or zincor both of theseingredients, other constituents such as manganese being present inrelatively small amounts, do not exhibit a sufficient resistance tocorrosion by water or even by damp air, and cannot be used atall when incontinuous contact with sea-water. Various attempts have been made torender the surfaces of these metals more resistant by applying coatings,but such attempts failed since corrosion often takes place to anincreased extent when the superficial protective layer is damaged.

The object of the invention is attained by the addition of furtheradditional metals to the alloys,v namely antimony or bismuth or both ofthese metals amounting in general to not less than 0.05% and not morethan 2% of the total.

The most diverse alloys of the kind referred to containing antimony orbismuth have proved distinctly superior, when exposed to the action of a3% solution of common salt, to alloys of the same kind which do notcontain antimony or bismuth; whilst the alloys containing antimony orbismuth shown an almost unaltered surface, the samples devoid ofantimony or bismuth were strongly corroded on carrying out thecomparative tests.

In general the lower limit of efficiency is given by additions of 0.05%,and it is'preferable not to exceed the upper limit of 2%.

From their position in the electrochemical series antimony and bismuthare more valuable than magnesium, and moreover do not form a solidsolution with thelatter; the assumption therefore would rather have beenthat the addition of these metals to the known alloys of mag-- nesiumwould involve decreasing their resistance to corrosion.

The magnesium-base alloys developed by the present invention show also aconsiderable increase in strength, without the elongation de-Application February 14, 1933,

In Austria February 19,

creasing. As the magnesium alloys of the kind hitherto in use (electron,Dow metal) have a comparatively small strength, this constitutes afurther advance of considerable importance, the more so as the specificgravity of the alloys is scarcely increased to any perceptible extent bythe small amount of the added metals.

Furthermore, the alloys according to the invention show in comparisonwith similarly composed known ele'ctron alloys an increase of thepermanent impact strength by The alloys may be used as cast alloys ormechanically worked alloys and may be improved by thermal treatments.

A satisfactory formula for an alloy according to my invention, in whichaluminium is the principal additional ingredientis as follows, viz:-magnesium 913%, aluminum 8%, manganese 0,2%, antimony 0,5%; for such analloy in which zinc is the principal additional ingredient satisfactoryformulse are as follows, viz :-magnesium 94.17%, zinc 4%, manganese 03%,antimony 1% magnesium 962%, zinc 3%, manganese 0,5%, bismuth 0,3%. Foran alloy including both aluminum and zinc the ifollowing compositionsmay be given by way of example, viz:-magnesium 935%, aluminum 4%, zinc1%, manganese 1%, antimony 0,51%; magnesium 90,3%, aluminum 5%, zinc 3%,manganese 1,2%, bismuth 0,5%;

loy containing from 80 to 98.8 per cent of magnesium, aluminum in anamount from 1 to 16 per cent, manganese in an amount. between 0.12 to 2per cent, and a metal selected from the group consisting of antimony andbismuth in an amount from 0.05 to 2 per cent, the alloy being moreresistant to corrosion than an alloy of the same composition but notcontaining a metal selected from the said group.

2. A low specific gravity magnesium base alloy, consisting of from 80 to98.8 per cent of magnesium, from 1 to 16 percent of aluminum, from 0.15to 2 per cent of manganese, and from 0.05 to 2 per cent of antimony. 3.A low specific gravity. magnesium base alloy, consisting of from 80 to98.8 per cent of magnesium, from 1 to 16 per cent of aluminum, from 0.15to 2 per cent ,of manganese, and from 0.05 to 2 per cent of bismuth.

4. A low specific gravity magnesium base alloy, consisting of from 30 to98.8 per cent of magnesium, from 1 to 16 per cent of aluminum, from 0.15to 2 per cent of manganese, and a metal selected from the groupconsisting of antimony and bismuth in an amount from 0.05 to 2 per cent.

5. As a new article of manufacture, an article resistant .to corrosionand formed from an alloy containing magnesium, aluminum and manganese,the magnesium being present in an amount from 80 to 98.8 per cent, thealuminum being present in an amount from 1 to 16 per cent, the amount ofmanganese being from 0.15 to 2 per cent, and the alloy containing from0.05 to 2 per cent of a metal selected from the group consisting ofantimony and bismuth, the alloy being more resistant to corrosion thanan alloy of the same composition but not containing a metal selectedfrom said group.

GEORG SCHICHTEL.

